COMETS TAILS.

Dominion, Volume 2, Issue 514, 22 May 1909, Page 12

COMETS TAILS.

JlY&rniY OF THEni KEFOLBION C?

TIIE SDN*. - . Tlia jpystcry of cotnofe' t»ila was tb« object of » lecture by jjr. Arthpr gtopicy I) - dingtpp, tjip. Royal It)stitirti<jp, liradooi recently. 'H#. wW tho, tel)weor cf Mwoliouso'a oouipt wiw -stiU tog cltB®TP4 » tlio Southern. HeppspJicrp. gw> an umisuiil opportunity fpr tho processes going pn,in (i punipit, afl4.tiM wropdraor ltoya) arrapgpd fof tho takittg of a lpng sonos of photographs at fyoqupart intcrvsik so as to obtain a kinowatogiipj} repaid it tlio-'ohapgos! place. Besidfls'its position thifi eojnot wsa, from another point of > view, ' remarkably kwentablo—nanioly, for studying the nitions in the tail —<uid nevor boforo had pliotograjitis been obtained, slifiTyjng spph an uaoont of ifttricato dotail" and arid contorted streamers. Tligao photograph* helped-them to study the groat outstanding problem in oomots—tho motions of tho particles of th?- tail and t)ie foroos which txpm them, . .

The tail streams out from the comet jn > too direction pearly' directly nwpy froni thp sup, ft':pr pot simply left behind by tho comet. It is driyon tiyaj frqpi l the sun, and , pay bo pither iq front or behind tho head in its orbital ( motion, according to circumstance?, ' \Yo are accustomed' tp regard thp, gun (is of ijn j'ttr'actiy© forpo, by which thp planets aro kept in their orpttg, and cohiojts heads also move under tho same law sg % as can bp ascertainoj. But tho taij particles of tho comot do not seam" to tjiis foroo, or, at legst, with then jt is pipro tiiirn oounWbalanoed by a repiiltho sbji jwhayei aq a contjp of ropulsioq pnd prgeii them' away. IV fa I«PS'ft. groat pan i» mj4«» staiifi jiOTT the pp cap thug play a doub(« 1 rpjp. hut various plausible explanations ors fprthponiing, ppd probably t(ip meet popular M that which; ascribes the . strpajpnjg - froip tho Bun to tho effept of ligpttfjressurp. l) cn ' ffldistion of any Iftadj pfnlKht, 'or " tho hfs.it frPfii a Are, f(iU§ op a ppiftpp, it exerts Jvprpssq.ro. cm that Swfnoo tending, to drive' it basic." «• llie prcssijre nf sunlight falling oil tho earth is ijojpetlling lib# 150,000 tons weight,' a force vhi.cll is. ni/jnfijpjppt tp make tho earth,budge so lppoh as pno hair'? breadth from .its pn-th. ' . "